A novel quantitative31P NMR spectroscopic analysis of hydroxyl groups in lignosulfonic acids
| Autor: | Bodo Saake, Jacob Podschun, Ralph Lehnen, Alexander Stücker |
|---|---|
| Rok vydání: | 2018 |
| Předmět: |
010405 organic chemistry
General Chemical Engineering General Engineering 02 engineering and technology 021001 nanoscience & nanotechnology 01 natural sciences 0104 chemical sciences Analytical Chemistry chemistry.chemical_compound chemistry Reagent Pyridine Organic chemistry Lignin Lignosulfonates Solubility 0210 nano-technology Derivatization Imide Quantitative analysis (chemistry) |
| Zdroj: | Analytical Methods. 10:3481-3488 |
| ISSN: | 1759-9679 1759-9660 |
| DOI: | 10.1039/c8ay01272e |
| Popis: | 31P nuclear magnetic resonance (NMR) spectroscopy is a common analytical approach for the quantitative determination of the different hydroxyl groups in technical lignins. However, the analysis of lignosulfonates with this method is more difficult due to solubility problems in the commonly used solvent systems. Hence, extensive derivatization procedures must be applied to facilitate a quantitative hydroxyl group analysis of the sulfonated lignins. In this study, we present an alternative and facile approach for the quantitative analysis of the hydroxylic environment in lignosulfonates. Technical lignosulfonates were transferred into the corresponding lignosulfonic acids by ion exchange treatment. After lyophilization, the samples were dissolved in a novel solvent system consisting of DMF/DMF-d7/pyridine (4.5 : 1 : 1; v/v) in the presence of an internal standard (endo-N-hydroxy-5-norbornene-2,3-dicarboxylic acid imide), relaxation agent and derivatization reagent (2-chloro-4,4,5,5-tetramethyl-1,3,2-dioxaphospholane). The accuracy of the experimental protocol was shown by analysis of lignin model compounds and by comparison with previously published derivatization procedures. |
| Databáze: | OpenAIRE |
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